Calendar arrangement for a timepiece

ABSTRACT

A timepiece calendar arrangement includes a single calendar disc having digits arranged around its periphery, and a viewing window arranged to mask all digits other than those corresponding to a given date. The digits are interlaced and the viewing window is formed from two separated portions, both portions being located away from a principal diametral axis of the timepiece.

United States Patent Erni et al.

[45] Aug. 26, 1975 CALENDAR ARRANGEMENT FOR A TIMEPIECE Inventors: Bruno Erni, Bienne; Pierre-Andre Beguin, Nods, both of Switzerland Assignee: Societe Suisse Pour llndustrie Horlogere Management Services S.A., Bienne, Switzerland Filed: Sept. 12, 1974 Appl. No.: 505,379

Foreign Application Priority Data Sept. 24, 1973 United Kingdom. 44582/73 US. Cl 58/5; 58/58; 58/127 R Int. Cl G04b 19/24; GO4b 19/06 Field of Search 58/4 R, 5, 58, 127 R [56] References Cited UNITED STATES PATENTS 3.712.043 l/l973 Egger et al 58/5 Primary ExaminerGeorge H. Miller, Jr. Attorney, Agent, or Firm-Griffin, Branigan and Butler 5 7 ABSTRACT A timepiece calendar arrangement includes a single calendar disc having digits arranged around its periphery, and a viewing window arranged to mask all digits other than those corresponding to a given date. The digits are interlaced and the viewing window is formed from two separated portions, both portions being located away from a principal diametral axis of the timepiece.

8 Claims, 7 Drawing Figures PATENTEDAUBZBIQYS 3,901,017

saw 1 [IF 5 v PATENTEB M182 6 I975 SHZET 5 BF 5 FIG. 7

CALENDAR ARRANGEMENT FOR A TIMEPIECE The present invention concerns a calendar arrangement for a timepiece which affords larger numbers and thus enhanced visibility.

At the present time, watches and other timepieces provided with calendars are commonplace. Modern timepieces are generally provided with a disc bearing the numbers of the days of the month from I 31 and the arrangement is such that the disc bearing the numbers is placed under the timepiece dial and is stepped once every 24 hours in order to permit reading of the current date through a window located in the dial. In general the windows are provided at locations such as 12 oclock, 3 o'clock or 6 oclock for convenience in reading and are located approximately at the outer circumference of the watch dial in order to enable the digits to be made as large as possible. Where Wristwatches are concerned and particularly ladies Wristwatches the digits are nevertheless for the most part very small and are evidently limited by the maximum diameter of the calendar dial which must be divided into 31 segments. Thus in smaller calibre Wristwatches the digits may become almost impossible to read.

Numerous attempts have been made to improve the readability of such digits and one well-known method is to provide a magnifying portion in the watch glass just above the viewing window. This has the disadvantage of distorting the digits which may bejust as bad for a person having poor eyesight as no magnification at all. Furthermore, the manufacture of the watch glass is greatly complicated and the arrangement becomes more expensive without necessarily providing much of an improvement.

Numerous other attempts have also been made to enhance visibility, notably by the use of two date dials, one of which carries the units digits and therefore needs only to provide 10 divisions and a second which provides the tens digits and therefore needs only four divisions. In all of these dual disc arrangements however, the mechanism itself is greatly complicated since a tens transfer mechanism is required and furthermore, such calendars require correction every month rather than for alternate months as in the single disc calendars.

The present calendar arrangement utilizes a single disc which can be produced at a cost no greater than present single disc calendars and provides greatly enhanced visibility. This is achieved by a novel arrangement of the digits on the disc, by a relocation of the viewing window and by dividing the viewing window into two separated portions.

The invention accordingly provides a calendar arrangement in a timepiece comprising, in combination, a single calendar disc having digits arranged around its periphery and a viewing window arranged to mask all digits other than those corresponding to a given date, characterized in that the digits are interlaced and the viewing window is formed from two separated portions, such portions being located in a position away from a principal diametral axis of the timepiece.

To enable better understanding of the invention reference will now be made to the accompanying drawings in which FIG. 1 illustrates a calendar timepiece according to the invention.

FIG. 2 illustrates the details of the calendar disc to be used in the invention.

FIG. 3 is a graphical showing of how the position and dimensions of the viewing windows may be chosen to ensure maximum visibility.

FIG. 4 is a graph showing the relations between the width of the window, the height thereof and the angular location of the inner window as shown in FIG. 3.

FIG. 5 and 6 show embodiments ofalternate possible lay-outs for the calendar disc.

FIG. 7 is a drawing illustrating the derivation of the equations for certain dimensions. The calendar timepiece illustrated in FIG. 1 may be conventional in all respects other than the calendar itself. Herein the normal single viewing window which might in other calendar watches be located at 12 oclock, 3 oclock or 6 oclock has been split into into two portions and is now located at about 4 The date shown is the 30th of the month which will be visible as separated numbers in the two separated window portions 1 and 2. The separation 3 serves the purpose of concealing figures shown in dotted outlines. The preceding date of 29th and the succeeding date of 31st are thus completely hidden from view, and it will be appreciated that without a separation such as 3 between windows 1 and 2, great confusion would result. It is also apparent that owing to the arrangement the digits in question are considerably larger than digits normally possible on a calendar disc.

The particular arrangement of the digits requires that they be interlaced as shown for example in FIG. 2. The precise orientation of the digits will in all cases depend on the precise location chosen for the viewing windows. However, as can be clearly seen from FIG. 2 the digits intended to be viewed at any one time would be arranged on a chord of the calendar disc. Each figure, instead of being either perpendicular to a radius as would be the case for a viewing window located at 3 oclock or parallel to the radius as would be the case for a viewing window located at 12 oclock or 6 oclock, is in fact arranged at an angle to the radius between 0 and and the angle of course depends on the precise location of the viewing windows. Since the digits are all in fact slanted in their orientation it becomes possible to effect a substantial increase in the dimensions thereof as will be immediately apparent from FIG. 2. Owing, however, to this increase the digits will be interlaced with one another. For this reason separation 3 is necessary so that only those digits corresponding to the current date are visible at any one time. Turning on to FIG. 3 and FIG. 4 we can see how the angular location of the viewing windows may be chosen in order to maximize the surface. With an arrangement such as that shown the width of the windows b)as a function of the angular displacement a) from a diametral axis of the watch passing from 3 oclock to 9 oclock may be determined by reference to FIG. 7 as follows,

Cosa (Tc/R and cos(a'+ 217/31) fi/R The angle between S and b is 217/31 therefore,

s/b Cos 21T/3 1.

Substituting for S and rearranging terms,

277 lCosa(.os (a+ 3 Cos 3] The height h of the windows may be determined as follows to g/R Sin a g g therefore g R Sin a.

u/g' Tan 211/31 therefore a R Sin a.Tan 21r/31.

Substituting for u and t and rearranging,

h R(Cos a Sin a.Tan 21'r/31 )Tan 41r/31.

The separation d between the two windows is determined as follows:

d= v w where w=b Cos 21r/3l and v 0.6 h Sin 27r/31, the factor 0.6 being determined approximately by measurement. Therefore,

d= b Cos 21r/3l +0.6 h Sin 217/31.

It should be noted that the factor 0.6, if varied will cause less than a 1% variation in the value of d. Furthermore, the value of d as calculated above is a minimum value andjt may be increased provided the overall diameter of the calendar disc is also increased.

By choosing a given diameter of the watch dial and by choosing various angular locations, it becomes possible to calcualte the values b, h and d according to the location of the viewing windows on the watch dial. This has been done as shown in FIG. 4 for a calendar dial having an external diameter of mm. Curves are shown in FIG. 4 which illustrate how the width b increases as the angle a approaches 90 and the height diminishes. By combining the two curves a value b X h may be obtained and this appears to have a maximum value at an angle of approximately 50. Obviously through use of the formulas shown this may be calculated analytically although as shown the calculations were actually made by a computer. It is equally possible to establish a good approximation by simple trial and error.

As shown in FIG. 3 a location was chosen in the first quadrant, i.e. between 2 oclock and 3 oclock. It is perfectly obvious that however, any of the other quadrants could equally well be chosen and in all cases the calculation would be performed in the same manner and results would be the same apart from the question of which quadrant. For the purpose of this description the principal diametral axes of the watch correspond to those passing respectively from 3 oclock to 9 oclock and from 12 oclock to 6 oclock. The first quadrant is between 3 oclock and 12 oclock, the second quadrant between 12 oclock and 9 oclock, the third quadrant between 9 oclock and 6 oclock and the fourth quadrant between 6 oclock and 3 oclock.

Aesthetic and practical considerations may combine in deciding which of the four quadrants the viewing windows should be located in. Location of these windows in the fourth quadrant as shown in FIG. 1 is not intended to be limiting in this respect.

For various reasons, mainly aesthetic, it may be desirable to locate the viewing windows and orient the digits in a manner whereby less than the maximum size is obtained. It will be clear that any location and arrangement in accordance with the invention away from the principle axes will achieve some increase in possible size of the digits: where aesthetic considerations are important this may well be less than the maximum. An individual designer in looking at the relative dimensions including of course the separation between the viewing windows may wish to employ and may also apply certain mathematical criteria in establishing proportions, such criteria being for example based on Fibonacci series. The verison of the invention as illustrated in FIG. 1, 2 and 3 concerns an arrangement in which digits of standard form may be displayed and wherein the separation 3 between two digits will be slightly greater than the width of a single digit. In this case the sides of each of the separated portions of the viewing window will be rectilinear in form.

In the version of the invention according to FIG. 5 the digits may be slightly distorted in form, the sides of the separated portions of the viewing window will be curvilinear and the separation between the two portions 3 will be almost exactly equal to the width of one digit.

In the FIG. 6 version the digits are still more distorted, the sides of the separated portions of the viewing window are likewise curvilinear in form and here the separation 3 between the digits is equal approximately to the width of two digits.

The lay-outs of FIG. 5 and 6 have been found to provide some further increase in the size of the digits at a cost of some distortion which may be of slight or no importance in accordance with the overall aesthetic considerations of a given watch design.

Relating to the versions of FIG. 1, 2 and 3 it will be noted that the digits in viewing position lie along a single chord of the disc which chord is parallel to the principal diametral axis passing through 3 oclock and 9 oclock. In still other versions of the invention it would be possible to locate the separated portions of the viewing window in a slightly staggered manner whereby each of two digits in viewing position was centered on a separate chord parallel to such principal diametral axis.

What we claim is: v

1. Calendar arrangement in a timepiece comprising, in combination, a single calendar disc having digits arranged around its periphery and a viewing window arranged to mask all digits other than those corresponding to a given date, characterized in that the digits are interlaced and the viewing window is formed from two separated portions, such portions being located in a position away from a principal diametral axis of the timepiece.

2. Calendar arrangement as in claim 1 characterized in that the viewing window and digits are oriented so that the digits in viewing position are centered along a single chord of the disc parallel to the principal diametral axis passing through 3 oclock and 9 oclock.

3. Calendar arrangement as in claim 1 characterized in that the viewing window and digits are orientated so that each digit in the viewing position is centered on an individual chord of the disc parallel to the principal diametral axis passing through 3 oclock and 9 oclock.

4. Calendar arrangement as in claim 1 characterized in that each of the separated portions of the viewing window is formed with rectilinear sides.

5. Calendar arrangement as in claim 4 characterized in that the distance between the two separated portions of the viewing window is slightly greater than the width of a digit.

6. Calendar arrangement as in claim 1 characterized in that each of the separated portions of the viewing window is formed with curvilinear sides.

in that the distance between the two separated portions of the viewing window is approximately equal to the width of two digits. 

1. Calendar arrangement in a timepiece comprising, in combination, a single calendar disc having digits arranged around its periphery and a viewing window arranged to mask all digits other than those corresponding to a given date, characterized in that the digits are interlaced and the viewing window is formed from two separated portions, such portions being located in a position away from a principal diametral axis of the timepiece.
 2. Calendar arrangement as in claim 1 characterized in that the viewing window and digits are oriented so that the digits in viewing position are centered along a single chord of the disc parallel to the principal diametral axis passing through 3 o''clock and 9 o''clock.
 3. Calendar arrangement as in claim 1 characterized in that the viewing window and digits are orientated so that each digit in the viewing position is centered on an individual chord of the disc parallel to the principal diametral axis passing through 3 o''clock and 9 o''clock.
 4. Calendar arrangement as in claim 1 characterized in that each of the separated portions of the viewing window is formed with rectilinear sides.
 5. Calendar arrangement as in claim 4 characterized in that the distance between the two separated portions of the viewing window is slightly greater than the width of a digit.
 6. Calendar arrangement as in claim 1 characterized in that each of the separated portions of the viewing window is formed with curvilinear sides.
 7. Calendar arrangement as in claim 6 characterized in that the distance between the two separated portions of the viewing window is approximately equal to the width of one digit.
 8. Calendar arrangement as in claim 6 characterized in that the distance between the two separated portions of the viewing window is approximately equal to the width of two digits. 